The technological basis for adaptive ion beam therapy at MedAustron: Status and outlook

Stock, Markus; Georg, Dietmar; Ableitinger, A.; Zechner, A.; Utz, A.; Mumot, M.; Kragl, G.; Hopfgartner, J.; Góra, J.; Böhlen, Till Tobias; Grevillot, L.; Kueß, Peter; Steininger, Phil; Deutschmann, H.; Vatnitsky, Stanislav

doi:10.1016/j.zemedi.2017.09.007

Cited by 60 publications

(65 citation statements)

References 47 publications

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“…Cone‐beam CT (CBCT) is widely used in photon radiotherapy clinics for patient setup and monitoring treatment response in the context of adaptive radiation therapy 1,2 . Recently, CBCT has also made its way into proton therapy centers 3–5 . The applicability of cone‐beam CT for tasks such as dose calculation or organ delineation is, however, limited by the reduced image quality when compared with regular CT. Cone‐beam CT image quality is afflicted by artifacts caused by patient 6 and detector 7 scatter, flat panel detector lag and ghosting, 8 as well as the usual beam‐hardening artifacts also found in regular CT, as summarized and corrected in Thing et al 9 .…”

Section: Introductionmentioning

confidence: 99%

“…1,2 Recently, CBCT has also made its way into proton therapy centers. [3][4][5] The applicability of cone-beam CT for tasks such as dose calculation or organ delineation is, however, limited by the reduced image quality when compared with regular CT. Cone-beam CT image quality is afflicted by artifacts caused by patient 6 and detector 7 scatter, flat panel detector lag and ghosting, 8 as well as the usual beam-hardening artifacts also found in regular CT, as summarized and corrected in Thing et al 9 These artifacts reduce contrast and cause generally incorrect CT numbers. Standard CBCT scans can therefore not be used for dose-calculation and replanning of the patient treatment, which is required for adaptive photon and proton radiotherapy.…”

Section: Introductionmentioning

confidence: 99%

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ScatterNet: A convolutional neural network for cone‐beam CT intensity correction

et al. 2018

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Using a deep convolutional neural network for CBCT intensity correction was shown to be feasible in the pelvic region for the first time. Dose calculation accuracy on CBCT was high for VMAT, but unsatisfactory for IMPT. With respect to the reference technique (CBCT ), the neural network enabled a considerable increase in speed for intensity correction and might eventually allow for on-the-fly shading correction during CBCT acquisition.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

ScatterNet: A convolutional neural network for cone‐beam CT intensity correction

et al. 2018

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“…MedAustron uses a 7-degree of freedom ceiling-mounted patient positioning system that allows moving the patient toward the treatment nozzle and reducing the air gap for fixed beamlines. 3 A floor-mounted photogrammetric tracking camera guarantees position accuracy even in non-isocentric conditions. Image-guided particle therapy (IGPT) is ensured by the table-mounted ImagingRing TM system.…”

Section: A Non-isocentric Treatment Concept At Medaustronmentioning

confidence: 99%

“…Layout of the MedAustron facility, including MAPTA, the three clinical treatment rooms, and the research room. Reproduced by permission of Elsevier Publishing.…”

Section: Introductionmentioning

confidence: 99%

Clinical implementation and commissioning of the MedAustron Particle Therapy Accelerator for non‐isocentric scanned proton beam treatments

et al. 2019

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Purpose This paper describes the clinical implementation and medical commissioning of the MedAustron Particle Therapy Accelerator (MAPTA) for non‐isocentric scanned proton beam treatments. Methods Medical physics involvement during technical commissioning work is presented. Acceptance testing procedures, including advanced measurement methods of intra‐spill beam variations, are defined. Beam monitor calibration using two independent methods based on a dose‐area product formalism is described. Emphasis is given to the medical commissioning work and the specificities related to non‐isocentric irradiation, since a key feature of MedAustron is the routine delivery of non‐isocentric scanned proton beam treatments. Results Key commissioning results and beam stability trend lines for more than 2 yr of clinical operation have been provided. Intra‐spill beam range, size, and position variations were within specifications of 0.3 mm, 15%, and 0.5 mm, respectively. The agreement between two independent beam monitor calibration methods was better than 1.0%. Non‐isocentric treatment delivery allowed lateral penumbra reduction of up to about 30%. Daily QA measurements of the beam range, size, position, and dose were always within 1 mm, 10%, 1 mm, and 2% from the baseline data, respectively. Conclusions Non‐isocentric treatments have been successfully implemented at MedAustron for routine scanned proton beam therapy using horizontal and vertical fixed beamlines. Up to now every patient was treated in non‐isocentric conditions. The presented methodology to implement a new Scanned Ion Beam Delivery (SIBD) system into clinical routine for proton therapy may serve as a guidance for other centers.

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“…28,35 Individual pencil beam physical properties at the nozzle exit (energy, position, beam spot size, and divergence) were calculated using a set of polynomial equations obtained from depth-dose profiles and spot reference measurements in the dedicated research room of the MedAustron Medical Physics, 47 (1), January 2020 (EBG MedAustron GmbH, Wiener Neustadt, Austria) ion beam therapy center. 35,42…”

Section: A Monte Carlo Simulationsmentioning

confidence: 99%

Benchmarking a GATE/Geant4 Monte Carlo model for proton beams in magnetic fields

et al. 2019

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Purpose: Magnetic resonance guidance in proton therapy (MRPT) is expected to improve its current performance. The combination of magnetic fields with clinical proton beam lines poses several challenges for dosimetry, treatment planning and dose delivery. Proton beams are deflected by magnetic fields causing considerable changes in beam trajectories and also a retraction of the Bragg peak positions. A proper prediction and compensation of these effects is essential to ensure accurate dose calculations. This work aims to develop and benchmark a Monte Carlo (MC) beam model for dose calculation of MRPT for static magnetic fields up to 1 T. Methods: Proton beam interactions with magnetic fields were simulated using the GATE/Geant4 toolkit. The transport of charged particle in custom 3D magnetic field maps was implemented for the first time in GATE. Validation experiments were done using a horizontal proton pencil beam scanning system with energies between 62.4 and 252.7 MeV and a large gap dipole magnet (B = 0-1 T), positioned at the isocenter and creating magnetic fields transverse to the beam direction. Dose was measured with Gafchromic EBT3 films within a homogeneous PMMA phantom without and with bone and tissue equivalent material slab inserts. Linear energy transfer (LET) quenching of EBT3 films was corrected using a linear model on dose-averaged LET method to ensure a realistic dosimetric comparison between simulations and experiments. Planar dose distributions were measured with the films in two different configurations: parallel and transverse to the beam direction using single energy fields and spread-out Bragg peaks. The MC model was benchmarked against lateral deflections and spot sizes in air of single beams measured with a Lynx PT detector, as well as dose distributions using EBT3 films. Experimental and calculated dose distributions were compared to test the accuracy of the model. Results: Measured proton beam deflections in air at distances of 465, 665, and 1155 mm behind the isocenter after passing the magnetic field region agreed with MC-predicted values within 4 mm. Differences between calculated and measured beam full width at half maximum (FWHM) were lower than 2 mm. For the homogeneous phantom, measured and simulated in-depth dose profiles showed range and average dose differences below 0.2 mm and 1.2%, respectively. Simulated central beam positions and widths differed <1 mm to the measurements with films. For both heterogenous phantoms, differences within 1 mm between measured and simulated central beam positions and widths were obtained, confirming a good agreement of the MC model. Conclusions: A GATE/Geant4 beam model for protons interacting with magnetic fields up to 1 T was developed and benchmarked to experimental data. For the first time, the GATE/Geant4 model was successfully validated not only for single energy beams, but for SOBP, in homogeneous and heterogeneous phantoms. EBT3 film dosimetry demonstrated to be a powerful dosimetric tool, once the film response function is LET corrected,...

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The technological basis for adaptive ion beam therapy at MedAustron: Status and outlook

Cited by 60 publications

References 47 publications

ScatterNet: A convolutional neural network for cone‐beam CT intensity correction

ScatterNet: A convolutional neural network for cone‐beam CT intensity correction

Clinical implementation and commissioning of the MedAustron Particle Therapy Accelerator for non‐isocentric scanned proton beam treatments

Benchmarking a GATE/Geant4 Monte Carlo model for proton beams in magnetic fields

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